The prototype of a CO2 sensor made of CuO-BaTiO3, which has capacitance sen
sitive effect, is designed based on the pn heterojunctions of CuO and BaTiO
3 semiconductors. The preparation of BaTiO3 semiconductor powders is pointe
d out, using the coprecipitation and semiconducting techniques. The charact
eristic quantities relating to the capacitance sensitive effect of the sens
or are studied systematically with the aid of a gas tester. A reasonable me
chanism of the sensor is proposed. (C) 2001 Published by Elsevier Science B
.V.